JP6322234B2 - Optical element holding structure, camera filter frame, camera filter unit, and imaging lens - Google Patents

Description

  The present invention relates to a holding structure that holds an optical element such as an optical filter or an optical lens with low stress. The present invention also relates to a camera filter frame and a camera filter unit that hold a filter with low stress, and an imaging lens that holds an optical lens with low stress.

  A filter unit for a camera attached to a lens barrel of an imaging lens is described in Patent Document 1. The camera filter unit of the same document prevents the optical filter from moving forward by contacting the optical filter with a disk-shaped optical filter, a cylindrical filter holding ring in which the optical filter is coaxially fitted, and the optical filter from the front. A front stopper and a rear stopper for preventing the optical filter from moving backward are provided. The front stopper is a protrusion protruding from the front end edge of the filter holding ring toward the inner peripheral side. The rear stopper is a caulking portion formed by caulking the rear end portion of the filter holding ring toward the inner peripheral side. The optical filter is sandwiched between a front stopper and a rear stopper.

JP 2010-1113016 A

  Here, if the stress (pressure) applied to the optical filter from the front and rear stoppers can be reduced, a more beautiful shot image or video can be obtained when shooting high resolution, which is many times higher than full high-definition. There is a possibility that.

  In view of this point, an object of the present invention is to provide a holding structure for an optical element that holds an optical filter and an optical lens with low stress. Another object of the present invention is to provide a camera filter frame and a camera filter unit that hold an optical filter with low stress. Furthermore, it is providing the imaging lens which hold | maintains an optical lens with low stress.

In order to solve the above-described problems, the optical element holding structure of the present invention includes a cylindrical body in which an optical element is coaxially inserted on the inner peripheral side, and an outer peripheral edge portion on the front surface of the optical element from the front in the axial direction. An abutting front stopper, a rear stopper adjacent to the optical element at the rear in the axial direction and facing an outer peripheral edge portion of the rear surface of the optical element, and an axis line between the front stopper and the rear stopper An adhesive that non-rotatably fixes the optical element held in a rotatable state around the cylindrical body, and the cylindrical body penetrates in a direction intersecting the axial direction. The front stopper is a protrusion protruding from the front end portion of the cylindrical body toward the inner peripheral side, and the rear stopper is provided by bending the rear end portion of the cylindrical body toward the inner peripheral side. cage, wherein the adhesive is the through hole To is interposed between the penetrated by said cylindrical body wherein the optical element between said cylindrical body and said optical element, said optical element is between abut the rear stopper to the front stopper A gap is opened and the adhesive is fixed to the cylinder by the adhesive .

In the conventional optical element holding structure in which the optical element is sandwiched from the front and rear, there is a limit in reducing the stress applied to the optical filter from the front stopper and the rear stopper. On the other hand, in the present invention, since the configuration in which the optical filter is not sandwiched is adopted, the stress applied to the optical filter can be brought close to zero. Moreover, this invention has the adhesive agent interposed between the said cylinder and the said optical element, and the said adhesive fixes the said optical element to the said cylinder so that rotation is impossible. Therefore, the optical element can be made non-rotatable without being sandwiched from the front-rear direction. Further, in the present invention, in order to interpose an adhesive between the cylinder and the optical element, the cylinder includes a through-hole penetrating in a direction intersecting the axial direction, and the adhesive includes the through-hole. Through the cylindrical body and the optical element. Further, in the present invention, the front stopper is a protrusion protruding from the front end portion of the cylindrical body toward the inner peripheral side, and the rear stopper is provided by bending the rear end portion of the cylindrical body toward the inner peripheral side. It has been. Therefore, it becomes easy to hold the optical element between the front stopper and the rear stopper.

In the present invention, the cylindrical body includes an annular groove on at least one of an outer peripheral surface and an inner peripheral surface, and the rear stopper bends a portion of the cylindrical body where the annular groove is formed to the inner peripheral side. It is desirable to be provided by. In this way, when the rear stopper is formed, it is only necessary to bend the portion of the cylindrical body that is thin due to the provision of the annular groove, so that the bending process can be performed with a relatively small force. As a result, the processing accuracy of the bending process is improved, so that the distance between the front stopper and the rear stopper can be managed with high accuracy. Moreover, in this invention, it is desirable to have a frame body which hold | maintains the said cylinder on the inner peripheral side. If it does in this way, optical elements, such as an optical filter held at a cylinder, can be attached to a lens barrel via a frame. Further, an optical element such as an optical lens held by the cylindrical body can be attached to an imaging device such as a camera or a projection device via a frame.

Next, the present invention relates to a cylindrical body in which an optical element is coaxially inserted on the inner peripheral side, and from the front in the axial direction.
A front stopper capable of coming into contact with the outer peripheral edge portion of the front surface of the optical element; a rear stopper adjacent to the optical element at the rear in the axial direction and facing the outer peripheral edge portion of the rear surface of the optical element; and the front stopper And an adhesive that non-rotatably fixes the optical element held in a rotatable state about an axis between the rear stopper and the cylindrical stopper, A through hole penetrating in a direction intersecting the axial direction, one of the front stopper and the rear stopper is formed integrally with the cylindrical body, and the other of the front stopper and the rear stopper is the It is attached to the inner peripheral surface portion of the cylindrical body, and the adhesive enters between the cylindrical body and the optical element through the through hole and is interposed between the cylindrical body and the optical element. The optical element is Characterized in that it is fixed to the cylindrical body by said adhesive with a gap between abutting the rear stopper to the front stopper.

In the conventional optical element holding structure in which the optical element is sandwiched from the front and rear, there is a limit in reducing the stress applied to the optical filter from the front stopper and the rear stopper. On the other hand, in the present invention, since the configuration in which the optical filter is not sandwiched is adopted, the stress applied to the optical filter can be brought close to zero. Moreover, this invention has the adhesive agent interposed between the said cylinder and the said optical element, and the said adhesive fixes the said optical element to the said cylinder so that rotation is impossible. Therefore, the optical element can be made non-rotatable without being sandwiched from the front-rear direction. Further, in the present invention, in order to interpose an adhesive between the cylinder and the optical element, the cylinder includes a through-hole penetrating in a direction intersecting the axial direction, and the adhesive includes the through-hole. Through the cylindrical body and the optical element. Further, according to the present invention, one of the front stopper and the rear stopper is formed integrally with the cylinder, and the other of the front stopper and the rear stopper is formed on an inner peripheral surface portion of the cylinder. It is attached. Therefore, it is easy to hold the optical element between the front stopper and the rear stopper.

In the present invention, it is desirable to have a frame that holds the cylindrical body on the inner peripheral side. If it does in this way, optical elements, such as an optical filter held at a cylinder, can be attached to a lens barrel via a frame. Further, an optical element such as an optical lens held by the cylindrical body can be attached to an imaging device such as a camera or a projection device via a frame.

Next, the present invention includes a cylindrical body in which an optical element is coaxially inserted on the inner peripheral side, a front stopper that can come into contact with the outer peripheral edge portion of the front surface of the optical element from the front in the axial direction, and the axial direction A rear stopper that is adjacent to the optical element at the rear and faces the outer peripheral edge portion of the rear surface of the optical element, and the optical that is held in a state of being rotatable about an axis between the front stopper and the rear stopper. An adhesive that non-rotatably fixes the element to the cylindrical body, and a frame that holds the cylindrical body on an inner peripheral side, the cylindrical body penetrating in a direction intersecting the axial direction A through-hole
The front stopper is provided on the cylinder, the rear stopper is provided on the frame, and the adhesive is interposed between the cylinder and the optical element via the through hole. And is interposed between the cylindrical body and the optical element, and the optical element abuts on the front stopper and forms a gap between the rear stopper and the adhesive to the cylindrical body. It is fixed.

In the conventional optical element holding structure in which the optical element is sandwiched from the front and rear, there is a limit in reducing the stress applied to the optical filter from the front stopper and the rear stopper. On the other hand, in the present invention, since the configuration in which the optical filter is not sandwiched is adopted, the stress applied to the optical filter can be brought close to zero. Moreover, this invention has the adhesive agent interposed between the said cylinder and the said optical element, and the said adhesive fixes the said optical element to the said cylinder so that rotation is impossible. Therefore, the optical element can be made non-rotatable without being sandwiched from the front-rear direction. Further, in the present invention, in order to interpose an adhesive between the cylinder and the optical element, the cylinder includes a through-hole penetrating in a direction intersecting the axial direction, and the adhesive includes the through-hole. Through the cylindrical body and the optical element. Further, according to the present invention, one of the front stopper and the rear stopper is formed integrally with the cylinder, and the other of the front stopper and the rear stopper is formed on an inner peripheral surface portion of the cylinder. It is attached. Therefore, it is easy to hold the optical element between the front stopper and the rear stopper. Furthermore, in this invention, it has a frame which hold | maintains the said cylinder on the inner peripheral side. Therefore, an optical element such as an optical filter held by the cylinder can be attached to the lens barrel via the frame.

In the present invention, a gap of 0.01 mm to 0.02 mm is formed between the cylindrical body and the annular outer peripheral surface of the optical element facing the cylindrical body in a direction orthogonal to the axial direction. There can be.

  Next, a camera filter frame according to the present invention has the optical element holding structure described above, and holds an optical filter as the optical element.

  According to the camera filter frame of the present invention, the optical filter can be held with low stress (pressure).

  A camera filter unit according to the present invention includes the optical element holding structure and an optical filter held on the inner peripheral side of the cylindrical body.

  According to the filter unit for a camera of the present invention, the stress (pressure) applied to the optical filter is low. Therefore, even when a camera filter unit is attached to the imaging lens, for example, when shooting with high resolution, a beautiful captured image or captured moving image can be obtained.

  In addition, an imaging lens of the present invention includes the above-described optical element holding structure and an optical lens held on the inner peripheral side of the cylindrical body.

  According to the imaging lens of the present invention, the stress (pressure) applied to the optical lens is low. Therefore, a beautiful photographed image or a photographed moving image can be obtained when photographing at a high resolution.

6 is a perspective view of a camera filter unit of Reference Example 1. FIG. It is the longitudinal cross-sectional view and partial expanded sectional view of the filter unit for cameras of the reference example 1. It is explanatory drawing of the assembly method of the filter unit for cameras. It is a Newton ring of an optical filter held in a camera filter frame and a Newton ring of only an optical filter. It is the longitudinal cross-sectional view and partial expanded sectional view of the filter unit for cameras of the reference example 2. It is explanatory drawing of the bending process which forms a rear side stopper. FIG. 3 is a partial enlarged cross-sectional view of the camera filter unit according to the first embodiment. It is the longitudinal cross-sectional view of the filter unit for cameras of the reference example 3, and the partial expanded sectional view. It is the longitudinal cross-sectional view and partial expanded sectional view of the filter unit for cameras of the reference example 4. It is the longitudinal cross-sectional view and partial expanded sectional view of an imaging lens.

  A camera filter unit to which the present invention is applied will be described below with reference to the drawings.

(Reference Example 1)
(overall structure)
FIG. 1 is a perspective view of a camera filter unit of Reference Example 1 having a configuration corresponding to that of the camera filter unit of the present invention. As shown in FIG. 1, a camera filter unit 1 of this example includes an optical filter (optical element) 2, a cylindrical filter holding ring (cylindrical body) 3 in which the optical filter 2 is fitted coaxially, and a filter holding unit. A cylindrical filter frame (frame body) 4 that holds the ring 3 coaxially from the outer peripheral side is provided. In the following description, the axis L direction of the filter holding ring and the filter frame 4 is defined as the front-rear direction X of the camera filter unit 1.

  The optical filter 2 and the filter holding ring 3 are arranged so as not to be exposed from the front and rear ends of the filter frame 4. On the outer peripheral surface of the filter frame 4, a frame-side male screw 5 is formed at a portion having a constant width from the rear edge toward the front X <b> 1. The frame-side male screw 5 is a mounting portion for mounting the camera filter unit 1 to a lens barrel or camera of an imaging lens. In this example, the pitch of the frame-side male screw 5 is 0.75 mm, which is a male screw generally formed as a mounting portion. The filter holding ring 3 and the filter frame 4 are made of a metal base material, and are made of aluminum in this example. The filter holding ring 3 and the filter frame 4 constitute a camera filter frame 6 that holds the optical filter 2.

(Optical filter)
2A is a longitudinal sectional view schematically showing the camera filter unit 1, and FIG. 2B is a partially enlarged sectional view in which the vicinity of the outer peripheral edge portion of the optical filter 2 is enlarged. As shown in FIG. 2A, the optical filter 2 has a disk shape and includes a front filter surface 11 and a rear filter surface 12 that are orthogonal to the axis L. As shown in FIG. 2B, a tapered annular chamfered surface (tapered rear surface portion) 13 that inclines toward the outer periphery toward the front X1 is continuously provided on the outer peripheral edge of the rear filter surface 12. Yes. An annular outer peripheral surface 14 having a constant diameter is continuous with the front end edge of the annular chamfered surface 13. The front filter surface 11 is continuous with the front end edge of the annular outer peripheral surface 14. Here, the annular chamfered surface 13 is generally provided in the optical filter. The optical filter 2 may be provided with a tapered annular chamfered surface that is inclined inward toward the front X1 between the annular outer peripheral surface 14 and the front filter surface 11.

(Filter retaining ring)
The filter holding ring 3 includes a front stopper 21 that protrudes inward on the front edge. The front stopper 21 is an annular protrusion. The annular front end surface of the front stopper 21 is a diffuse reflection surface by forming a plurality of grooves concentric with the filter holding ring 3. An annular rear end surface (rear facing surface) 21 a of the front stopper 21 is a flat surface orthogonal to the axis L. In the front stopper 21, the annular rear end surface 21 a abuts against the outer peripheral edge of the front filter surface 11 of the optical filter 2 from the front X 1 to prevent the optical filter 2 from moving to the front X 1.

  The filter holding ring 3 is a rear stopper 22 whose rear end extends along the annular chamfered surface 13. Here, as shown in FIG. 2 (b), the filter holding ring 3 is an outer periphery of a portion located on the outer side in the radial direction of the corner 15 at the boundary between the annular chamfered surface 13 and the annular outer peripheral surface 14 of the optical filter 2. An annular groove 23 is provided on the surface. The rear stopper 22 is formed by bending a portion where the annular groove 23 is provided along the corner portion 15 toward the inner peripheral side.

  In the state shown in FIG. 2, that is, in the state in which the camera filter unit is assembled, the annular rear end surface 21 a of the front stopper 21 is in contact with the entire outer periphery of the front filter surface 11 of the optical filter 2. On the other hand, the rear stopper 22 faces the annular chamfered surface 13 with a very narrow gap of about 0.02 mm to 0.04 mm. The rear end of the rear stopper 22 is located in the middle of the annular chamfer 13. That is, the rear end of the filter holding ring 3 is located in front X1 with respect to the rear filter surface 12 of the optical filter 2.

  In the filter holding ring 3, a ring-side annular inner peripheral surface 24 having a constant diameter is provided at a portion between the front stopper 21 and the rear stopper 22. There is a gap of about 0.01 mm to 0.02 mm on one side between the ring-side annular inner peripheral surface 24 and the annular outer peripheral surface 14 of the optical filter 2.

  On the outer peripheral surface of the filter holding ring 3, a ring-side male screw (cylinder-side male screw) 25 is formed in a region having a constant width from the front end edge toward the rear X2. The pitch of the ring-side male screw 25 is 0.75 mm. A smooth ring-side annular outer peripheral surface 26 having a constant diameter is provided between the formation region Q of the ring-side male screw 25 and the annular groove 23 on the outer peripheral surface of the filter holding ring 3. The ring-side annular outer peripheral surface 26 is positioned slightly on the inner peripheral side with respect to the ring-side male screw 25, and a ring-side annular rearward surface 27 that makes them continuous is provided between the ring-side annular outer peripheral surface 26 and the ring-side male screw 25. Is provided.

(Filter frame)
On the inner peripheral surface of the filter frame 4, a frame-side female screw (frame-side female screw) 31 is formed in a region having a constant width from the front end edge toward the rear X2. The ring-side male screw 25 is screwed into the frame-side female screw 31, and the filter holding ring 3 is screwed into the filter frame 4 from the front X1. Here, the width dimension of the formation region R of the frame-side female screw 31 is longer than the width dimension of the formation region Q of the ring-side male screw 25. Therefore, in a state where the ring-side male screw 25 is screwed into the frame-side female screw 31 and the filter holding ring 3 is held by the filter frame 4, the front end portion of the frame-side female screw 31 is exposed. The exposed front end portion of the frame-side female screw 31 is used as a lens cap mounting portion or a connecting portion for connecting another camera filter unit. The pitch of the frame-side female screw 31 is 0.75 mm, which is a female screw generally formed as a mounting portion.

  The filter frame 4 includes a second rear stopper 32 that protrudes to the inner peripheral side at the rear end. The second rear stopper 32 is an annular stepped portion, and includes an annular front end face 32a facing the front X1 and an annular inner peripheral face 32b facing the inner peripheral side. The annular front end surface 32a is a flat surface orthogonal to the axis L, and is in contact with the rear filter surface 12 of the optical filter 2 held by the filter holding ring 3 from the rear X2.

  On the inner peripheral surface of the filter frame 4, a frame-side annular inner peripheral surface 33 having a constant diameter is provided between the formation region R of the frame-side female screw 31 and the annular front end surface 32 a. The frame-side annular inner peripheral surface 33 is located slightly on the inner peripheral side with respect to the frame-side female screw 31, and the frame-side annular forward-facing surface that continues between the frame-side annular inner peripheral surface 33 and the frame-side female screw 31. 34 is provided. The annular inner peripheral surface 32b extends in parallel with the axis L. In a state where the filter holding ring 3 is held on the inner peripheral side of the filter frame 4, the frame-side annular inner peripheral surface 33 and the ring-side annular outer peripheral surface 26 face each other with a small gap.

  Here, the filter holding ring 3 is in a state in which the ring-side male screw 25 is screwed up to a middle position of the frame-side female screw 31 of the filter frame 4. The filter holding ring 3 is fixed to the filter frame 4 in a relatively non-rotatable state by an adhesive 35 interposed between the filter frame 4 and the filter frame 4. The adhesive 35 is formed between the frame-side annular inner peripheral surface 33 and the ring-side annular outer peripheral surface 26, between the frame-side annular forward facing surface 34 and the ring-side annular rearward surface 27, and between the frame-side female screw 31 and the ring-side male screw 25. It is interposed at least at one location.

(Assembly method of camera filter unit)
FIG. 3 is an explanatory view of an assembling method of the camera filter unit 1. As shown in FIG. 3A, when the camera filter unit 1 is manufactured, first, the optical filter 2 is attached from the rear X2 to the cylindrical filter holding ring 3 in a state where the rear stopper 22 is not provided. Fit. Next, a bending process is performed in which a portion of the rear end portion of the filter holding ring 3 that is located on the outer side in the radial direction of the corner portion 15 of the optical filter 2 is bent inward. As a result, the optical filter 2 is held by the filter holding ring 3 in a state in which the optical filter 2 can rotate relative to the axis L.

  In the bending process, as shown in FIG. 3B, the rear end portion of the filter holding ring 3 is set to the corner portion 15 of the optical filter 2 with the front filter surface 11 of the optical filter 2 in contact with the front stopper 21. Bend along. At this time, since the portion where the annular groove 23 is formed is located outside the corner portion 15 in the radial direction, the filter holding ring 3 is bent toward the inner peripheral side from the portion where the annular groove 23 is formed. Here, the portion where the annular groove 23 is formed is thinner than the front and rear portions. Therefore, the bending process in which the rear end portion of the filter holding ring 3 is the rear stopper 22 along the annular chamfered surface 13 can be performed with a relatively weak force. Therefore, it can suppress that the optical filter 2 is stressed at the time of a bending process. Further, since the filter holding ring 3 can be bent with a weak force, the accuracy of the bending process is increased. Accordingly, the optical filter 2 can be held by the filter holding ring 3 while being able to rotate around the axis L and in a state where the play is suppressed.

  When the rear stopper 22 is formed, the optical filter 2 is fitted coaxially into the filter holding ring 3 and is held between the front stopper 21 and the rear stopper 22. In this state, the optical filter 2 can rotate relative to the filter holding ring 3 around the axis L. That is, when the bending process is completed, the optical filter 2 is held in a state of being in partial contact with the ring-side annular inner peripheral surface 24 of the filter holding ring 3. A gap is partially formed between the side annular inner peripheral surfaces 24. Further, when the optical filter 2 is set in a posture perpendicular to the axis L, the entire circumference of the outer peripheral edge of the front filter surface 11 abuts on the front stopper 21, and the entire circumference of the annular chamfered surface 13 is the rear stopper 22. It is in a state where a state of abutting is not formed. Accordingly, the optical filter 2 rotates relative to the filter holding ring 3.

  In this example, a gap of about 0.01 mm to 0.02 mm is formed between the annular outer peripheral surface 14 of the optical filter 2 and the ring-side annular inner peripheral surface 24 of the filter holding ring 3. Further, when the optical filter 2 is disposed at a position away from both the front stopper 21 and the rear stopper 22, the annular chamfered surface 13 of the optical filter 2 is disposed between the front filter surface 11 and the front stopper 21 of the optical filter 2. A gap of about 0.01 mm to 0.02 mm is formed between the front stopper surface 22a of the rear stopper 22 and the tapered front surface 22a. Therefore, for example, when holding the outer peripheral surface of the filter holding ring 3 with one hand and lightly grasping the optical filter 2 from both sides in the direction of the axis L with the thumb and forefinger of the other hand, the filter holding ring 3 with a light force. And the optical filter 2 can be relatively rotated about the axis L. Here, since the optical filter 2 is held by the filter holding ring 3 in a relatively rotatable state, the stress (pressure) applied to the optical filter 2 is close to zero.

  Next, an adhesive 35 is applied to the entrance angle between the ring-side annular outer peripheral surface 26 and the ring-side annular rearward surface 27 of the filter holding ring 3. Thereafter, as shown in FIG. 3C, the filter holding ring 3 is inserted into the filter frame 4, the ring-side male screw 25 is screwed into the frame-side female screw 31, and the filter holding ring 3 is screwed.

  When the filter holding ring 3 is screwed, the optical filter 2 is brought into contact with the front stopper 21 of the filter holding ring 3. Then, the ring-side male screw 25 is not screwed to the rear end of the frame-side female screw 31, and the rear filter surface 12 of the optical filter 2 is connected to the second rear-side stopper 32 of the filter frame 4 as shown in FIG. At the time of contact, the screwing is stopped. Thereby, the attitude | position of the optical filter 2 is prescribed | regulated and the shakiness of the optical filter 2 is eliminated. Further, the optical filter 2 cannot be rotated relative to the filter holding ring 3.

  After that, as shown in FIG. 3E, the filter holding ring 3 is further rotated in the screwing direction T by a preset angle θ. Thereby, a slight force is applied to the optical filter 2 from the front stopper 21 and the second rear stopper 32.

  After that, it waits for the filter holding ring 3 and the filter frame 4 to be fixed in a state where relative rotation is impossible due to the curing of the adhesive 35. Thereby, the assembly of the camera filter unit 1 is completed.

  In this example, the set angle θ is 5 °. Therefore, after the filter holding ring 3 is rotated 5 ° in the screwing direction T from the angular position at the time when the rear filter surface 12 of the optical filter 2 contacts the second rear stopper 32 of the filter frame 4. It is fixed to the filter frame 4. Here, since the pitch of the frame-side female screw 31 is 0.75 mm, the filter holding ring 3 is moved backward X2 by about 0.01 mm on the filter frame 4 from the time when the screwing is stopped by screwing the filter holding ring 3 by 5 °. To do. As a result, a slight force is applied to the optical filter 2 from the front stopper 21 and the second rear stopper 32, so that the optical filter 2 is securely fixed.

  If the set angle θ is set to 7 ° or less, the moving distance of the filter holding ring 3 on the filter frame 4 when the filter holding ring 3 is rotated by the set angle θ is 0.015 mm or less, and the front stopper 21 and the second stopper 21 2 the rear stopper 32 abuts against the optical filter 2 with a relatively weak force.

(Function and effect)
According to this example, the optical filter 2 is held by the filter holding ring 3 so as to be relatively rotatable about the axis L. Therefore, the stress (pressure) applied to the optical filter 2 held by the filter holding ring 3 is close to zero.

  In this example, the front filter 21 and the second rear stopper 32 are brought into contact with the optical filter 2 from the front and rear with a slight force to fix the optical filter 2 so as not to be relatively rotatable. Here, since the optical filter 2 is fitted coaxially to the filter holding ring 3 and is held between the front stopper 21 and the rear stopper 22, the optical filter 2 is held by the front stopper 21 and the second rear stopper 32. The optical filter 2 does not fall off even if it is not sandwiched with force applied from the front and rear. Therefore, the optical filter 2 can be prevented from falling off by merely bringing the front stopper 21 and the second rear stopper 32 into contact with the optical filter 2 with a slight force, and the stress applied to the optical filter 2 can be suppressed.

  FIG. 4A shows a Newton ring of the optical filter 2 in the camera filter unit 1 of this example, and FIG. 4B shows a Newton ring of the optical filter 2 only. As can be seen from FIG. 4, there is almost no difference between the Newton ring of the optical filter 2 and the Newton ring of the optical filter 2 only in the camera filter unit 1 of this example. In other words, according to this example, the optical filter 2 has almost no difference in surface accuracy even when it is held by the camera filter frame 6 or when it exists alone.

  In this example, the pressure at which the front stopper 21 and the second rear stopper 32 abut on the optical filter 2 can be adjusted by adjusting the screwing amount of the filter holding ring 3 into the filter frame 4. For example, the stress applied to the optical filter 2 can be further reduced by setting the setting angle θ to be smaller than 5 °. Furthermore, the filter holding ring 3 and the filter frame 4 are fixed in a state where the relative position is defined by an adhesive 35 interposed therebetween. Therefore, after adjusting the screwing amount of the filter holding ring 3 into the filter frame 4, the distance between the front stopper 21 and the second rear stopper 32 does not change, and the stress applied to the optical filter 2 changes. There is nothing.

  Furthermore, in this example, the rear end of the filter holding ring 3 (the rear end of the rear stopper 22) is located in front X1 of the rear filter surface 12, so that the second rear stopper 32 is placed on the optical filter 2. When abutting, the filter holding ring 3 and the second rear stopper 32 do not interfere with each other. Therefore, the second rear stopper 32 can be a simple shape like an annular stepped portion.

  Further, in this example, since the filter frame 4 that holds the filter holding ring 3 from the outer peripheral side is provided, the second rear stopper 32 that comes into contact with the optical filter 2 held by the filter holding ring 3 from the rear X2 is provided. Is easy. Furthermore, since the filter frame 4 is provided, it is easy to provide the filter frame 4 with a lens barrel of the imaging lens and a camera mounting portion.

(Modification of Reference Example 1)
In the above example, the filter holding ring 3 includes the annular groove 23, but the annular groove 23 may be omitted. In the above example, the annular groove 23 is provided on the outer peripheral surface of the filter holding ring 3. You may provide in the site | part located in. Further, the annular groove 23 can be provided on both the outer peripheral surface and the inner peripheral surface of the filter holding ring 3.

In the above example, the rear end of the filter holding ring 3 (the rear end of the rear stopper 22) is located in front X1 of the rear filter surface 12 of the optical filter 2, but the rear end of the filter holding ring 3 is the rear filter. You may protrude in the back X2 from the surface 12. In this case, a recess is provided in the annular front end surface 32a of the second rear stopper 32, and the protruding rear end of the filter holding ring 3 is disposed in this recess. Accordingly, the second rear stopper 32 is brought into contact with the rear filter surface 12 while avoiding interference between the second rear stopper 32 and the rear end of the filter holding ring 3.

  In the above example, when the filter holding ring 3 is screwed into the filter frame 4, the adhesive 35 is applied to the outer peripheral surface of the filter holding ring 3, but the adhesive is applied to the inner peripheral surface of the filter frame 4. Also good. In this case, an adhesive can be applied to the frame side annular inner peripheral surface 33 or the frame side annular forward facing surface 34.

  Here, the set angle θ may be set to 0 °. That is, when the rear filter surface 12 of the optical filter 2 comes into contact with the second rear stopper 32 of the filter frame 4, the screwing of the filter holding ring 3 into the filter frame 4 is stopped, and the filter holding ring 3 and the filter The frame 4 can also be fixed.

  Further, as the frame-side female screw 31, a female screw having a pitch of 0.5 mm or a female screw having a pitch of 1 mm may be provided. When a female screw having a pitch of 0.5 mm is provided as the frame-side female screw 31, the set angle θ can be set to 10 ° or less. When a female screw having a pitch of 1 mm is provided as the frame-side female screw 31, the set angle θ can be set to 5 ° or less. In this way, when the filter holding ring 3 is rotated by the set angle θ, the moving distance of the filter holding ring 3 on the filter frame 4 is 0.015 mm or less, and the front stopper 21 and the second rear stopper 32 are It abuts on the optical filter 2 with a relatively weak force.

(Reference Example 2)
FIG. 5A is a longitudinal sectional view schematically showing the camera filter unit of Reference Example 2, and FIG. 5B is the vicinity of the outer peripheral edge portion of the optical filter 2 in the camera filter unit of Reference Example 2. It is the partial expanded sectional view which expanded. The camera filter unit 1A of this example is different from the camera filter unit 1 of Reference Example 1 in the position and shape of the annular groove 23A. Further, the camera filter unit 1A of this example does not have the second rear stopper. Since the camera filter unit 1A of the present example has the same configuration as that of the camera filter unit 1 of the reference example 1, the corresponding parts are denoted by the same reference numerals, and description thereof is omitted.

  As shown in FIG. 5A, the camera filter unit 1A of this example includes an optical filter 2, a filter holding ring (cylinder) 3 in which the optical filter 2 is coaxially fitted on the inner peripheral side, and a filter holding unit. It has a filter frame (frame body) 4 that holds the ring 3 coaxially from the outer peripheral side. The filter holding ring 3 and the filter frame 4 constitute a camera filter frame 6 that holds the optical filter 2.

  The filter holding ring 3 includes a front stopper 21 that protrudes inward on the front edge. As shown in FIG. 5B, the annular rear end surface (rear facing surface) 21 a of the front stopper 21 is a flat surface orthogonal to the axis L. The front stopper 21 can come into contact with the optical filter 2 from the front X1, and prevents the optical filter 2 from moving forward X1. Further, the rear end portion of the filter holding ring 3 is a rear stopper 22 that extends along the annular chamfered surface (tapered rear surface portion) 13 of the optical filter 2. The rear stopper 22 can contact the optical filter 2 from the rear X2, and prevents the optical filter 2 from moving to the rear X2.

  The filter frame 4 includes a rear projection 41 at the rear end. The rear protrusion 41 is an annular protrusion that protrudes from the filter frame 4 to the inner peripheral side at a constant height, and includes an annular front end surface 41a facing the front X1 and an annular inner peripheral surface 41b facing the inner peripheral side. The annular inner peripheral surface 41 b is located on the inner peripheral side with respect to the annular chamfered surface 13 of the optical filter 2. The annular front end surface 41 a is a flat surface orthogonal to the axis L and extends in a direction orthogonal to the axis L.

  The filter holding ring 3 is screwed and fixed to the filter frame 4 until the ring-side annular rearward surface 27 continuous behind the ring-side male screw 25 and the frame-side annular forward surface 34 of the filter frame 4 abut. An adhesive 35 can be used to fix the filter holding ring 3 to the filter frame 4.

  In a state where the filter holding ring 3 is held by the filter frame 4, a gap is formed between the annular front end face 41 a of the rear protrusion 41 and the rear filter face 12 of the optical filter 2. That is, the rear protrusion 41 of the filter frame 4 and the optical filter 2 are not in contact. Further, when the camera filter unit 1A is viewed from the rear X2 in the axis L direction, the rear stopper 22 and the rear protrusion 41 overlap with each other, and the rear stopper 22 is hidden by the rear protrusion 41. A gap H is formed between the rear end of the rear stopper 22 and the annular front end face 41 a of the rear protrusion 41. The gap H is 0.02 mm or less.

  Here, with reference to FIG. 6, the formation method of the rear side stopper 22 in this example is demonstrated. FIG. 6 is an explanatory diagram of a method for forming the rear stopper 22. As shown in FIG. 6A, the rear end portion of the filter holding ring 3 extends in parallel with the annular outer peripheral surface 14 of the optical filter 2 before the rear stopper 22 is provided. The filter holding ring 3 includes an annular groove 23A on the inner peripheral surface thereof. The annular groove 23 </ b> A is provided in a portion located on the radially outer side of the corner portion 15 at the boundary between the annular chamfered surface 13 and the annular outer peripheral surface 14 of the optical filter 2. The annular groove 23A is a triangle whose cross-sectional shape when the filter holding ring 3 is cut along a plane including the axis L is tapered toward the outer peripheral side. The annular groove 23A is defined by an annular rearward surface that is orthogonal to the axis L and a tapered surface that is inclined inward from the outer peripheral end of the rearward surface toward the inner peripheral side.

  As shown in FIG. 6B, the rear stopper 22 is formed by bending a portion of the filter holding ring 3 where the annular groove 23A is provided to the inner peripheral side. More specifically, the rear stopper 22 has an inner periphery on the rear end portion of the filter holding ring 3 until the annular groove 23A is closed (until the groove has a triangular cross-sectional shape). It is provided by bending to the side. Here, the angle of the apex angle of the triangle serving as the bottom of the annular groove 23 </ b> A is a predetermined angle corresponding to the inclination angle of the annular chamfered surface 13 of the optical filter 2. As a result, when the rear end portion of the filter holding ring 3 is bent toward the inner peripheral side until the annular groove 23 </ b> A is closed, the forward facing surface of the rear stopper 22 becomes a tapered surface along the annular chamfered surface 13.

  In a state where the optical filter 2 is held between the front stopper 21 and the rear stopper 22, the optical filter 2 can rotate relative to the filter holding ring 3 around the axis L. That is, a gap of about 0.01 mm to 0.02 mm is formed between the annular outer peripheral surface 14 of the optical filter 2 and the ring-side annular inner peripheral surface 24 of the filter holding ring 3. Further, when the front filter surface 11 of the optical filter 2 is brought into contact with the front stopper 21, the annular chamfered surface 13 of the rear filter surface 12 of the optical filter 2 and the tapered forward surface 22a of the rear stopper 22 are provided. Is formed with a gap G of 0.03 mm or less.

(Function and effect)
According to this example, the optical filter 2 is held by the filter holding ring 3 so as to be relatively rotatable about the axis L. Therefore, the stress (pressure) applied to the optical filter 2 held by the filter holding ring 3 is close to zero.

Here, the camera filter unit 1 </ b> A of the present example does not include the second rear stopper that contacts the optical filter 2 from behind. However, in this example, the gap G between the optical filter 2 and the forward facing surface 22a of the rear stopper 22 is 0.03 mm or less and is narrow. Therefore, the optical filter 2 is not rattled between the front stopper 21 and the rear stopper 22, and the optical filter 2 is maintained in a state of being held coaxially with the filter holding ring 3. If the gap G is set to 0.05 mm or less, the optical filter 2 held by the camera filter frame 6 will not rattle. Therefore, the camera filter unit 1A can be practically used when it is mounted on a lens barrel and mounted on a camera.

  Further, in this example, since the filter frame 4 that holds the filter holding ring 3 from the outer peripheral side is provided, the filter frame 4 can be provided with a lens barrel of the imaging lens or a mounting portion to the camera.

  Furthermore, in this example, the rear protrusion 41 provided on the filter frame 4 protrudes to the inner peripheral side with respect to the rear stopper 22, and covers the rear stopper 22 from the rear X2 in the axis L direction. Accordingly, the rear stopper 22 can be protected by the rear protrusion 41. In this example, the gap H between the rear end of the rear stopper 22 and the annular front end surface 41a of the rear protrusion 41 is set to 0.02 mm or less. Therefore, when the rear stopper 22 formed by bending the inner periphery is going to be deformed to the outer periphery, the rear end of the rear stopper 22 and the rear protrusion 41 interfere with each other. In other words, the filter frame 4 includes an interference portion (rear protrusion 41) that interferes when the rear stopper 22 is displaced toward the outer peripheral side and prevents the rear stopper 22 from being deformed toward the outer peripheral side. Accordingly, the optical filter 2 is maintained in a state where it is held coaxially with the filter holding ring 3.

  Further, the rear stopper 22 can be provided so that the forward facing surface 22 a becomes an annular surface along the outer peripheral edge portion of the rear filter surface 12 of the optical filter 2. That is, when the rear stopper 22 is formed, the rear end portion of the rear stopper 22 is bent at a right angle to the inner peripheral side, and the front surface 22a is made a flat surface perpendicular to the axis L, so that the rear stopper 22 ( The forward facing surface 22a) may be capable of coming into contact with the rear filter surface 12 from the rear. Also in this case, if the gap G between the optical filter 2 formed when the optical filter 2 is brought into contact with the front stopper 21 and the front surface 22a of the rear stopper 22 is 0.05 mm or less, the optical The filter 2 can be held coaxially on the filter holding ring 3 in a rotatable state. In this case, the cross-sectional shape of the annular groove 23A formed on the inner peripheral surface of the filter holding ring 3 can be a rectangle.

Example 1
FIG. 7 is a partially enlarged cross-sectional view in which the vicinity of the outer peripheral edge portion of the optical filter 2 in the camera filter unit of Embodiment 1 is enlarged. The camera filter unit 1A ′ according to the first embodiment has the same configuration as that of the camera filter unit 1A according to the second embodiment. Therefore, the corresponding parts are denoted by the same reference numerals and the description thereof is omitted.

  As shown in FIG. 7, the camera filter unit 1 </ b> A ′ of this example includes an adhesive injection hole (through hole) 47 through which the filter holding ring 3 penetrates in a direction orthogonal to the axis L. The adhesive injection hole 47 has a tapered inner peripheral surface with a smaller inner diameter dimension from the outer peripheral side toward the inner peripheral side. Three adhesive injection holes 47 are provided at equiangular intervals. The camera filter unit 1 </ b> A ′ of this example includes an adhesive 48 interposed between the annular outer peripheral surface 14 of the optical filter 2 and the ring-side annular inner peripheral surface 24 of the filter holding ring 3. The adhesive 48 enters between the filter holding ring 3 and the optical filter 2 through the adhesive injection hole 47. In the optical filter 2, the outer peripheral edge portion of the front filter surface 11 is in contact with the annular rear end surface (rear surface) 21 a of the front stopper 21. The adhesive 48 fixes the optical filter 2 in contact with the front stopper 21 to the filter holding ring 3 so as not to rotate.

According to this example, the same effect as the camera filter unit 1A of the reference example 2 can be obtained. Moreover, according to this example, the rotation around the axis L of the optical filter 2 can be prevented. Furthermore, according to this example, the posture of the optical filter 2 can be accurately defined as the posture in contact with the front stopper 21, and the posture can be maintained.

  In the camera filter unit 1A ′ of the first embodiment, the number of the adhesive injection holes 47 provided in the filter holding ring 3 may be one, two, or four or more.

(Reference Example 3)
FIG. 8A is a longitudinal sectional view schematically showing the camera filter unit of Reference Example 3, and FIG. 8B is the vicinity of the outer peripheral edge portion of the optical filter 2 in the camera filter unit of Reference Example 3. It is the partial expanded sectional view which expanded. In the camera filter unit 1 </ b> B of this example, a rear stopper 45 that prevents the optical filter 2 from moving backward X <b> 2 is provided on the filter frame 4. Since the camera filter unit 1B of this example has the same configuration as the camera filter unit 1 of Reference Example 1, the corresponding parts are denoted by the same reference numerals and description thereof is omitted.

  As shown in FIG. 8A, a camera filter unit 1B according to the present invention includes an optical filter 2, a filter holding ring 3 (cylindrical body) 3 in which the optical filter 2 is coaxially fitted on the inner peripheral side, a filter A filter frame 4 (frame body) 4 that holds the holding ring 3 coaxially from the outer peripheral side is provided. The filter holding ring 3 and the filter frame 4 constitute a camera filter frame 6 that holds the optical filter 2.

  The filter holding ring 3 includes a front stopper 21 that protrudes inward on the front edge. An annular rear end surface (rear facing surface) 21 a of the front stopper 21 is a flat surface orthogonal to the axis L. The front stopper 21 can come into contact with the optical filter 2 from the front X1, and prevents the optical filter 2 from moving forward X1. The rear portion of the filter retaining ring 3 extends in parallel with the annular outer peripheral surface 14 of the optical filter 2. That is, the rear portion of the filter retaining ring 3 has a constant diameter dimension. Here, the width dimension W1 of the ring-side annular inner peripheral surface 24 extending from the front stopper 21 to the rear X2 in the filter holding ring 3 is longer than the thickness dimension D1 of the optical filter 2. In this example, the difference between the width dimension W1 of the ring-side annular inner peripheral surface 24 and the thickness dimension D1 of the optical filter 2 is 0.03 mm or less. Further, between the annular outer peripheral surface 14 of the optical filter 2 fitted on the inner peripheral side of the filter holding ring 3 and the ring-side annular inner peripheral surface 24 of the filter holding ring 3, a thickness of about 0.01 mm to 0.02 mm. The gap is formed.

  The filter frame 4 includes a rear stopper 45 at the rear end. The rear stopper 45 is an annular protrusion that protrudes from the filter frame 4 to the inner peripheral side at a constant height, and includes an annular front end surface (forward facing surface) 45a facing the front X1 and an annular inner peripheral surface 45b facing the inner peripheral side. Is provided. The annular inner peripheral surface 45 b of the rear stopper 45 is located on the inner peripheral side with respect to the annular chamfered surface 13 of the optical filter 2. The annular front end surface 45 a is a flat surface orthogonal to the axis L, and extends along the rear filter surface 12 of the optical filter 2. When viewed from the rear X2 in the direction of the axis L, the rear stopper 45 overlaps the outer peripheral edge portion of the rear filter surface 12 and the annular chamfered surface 13 which are the outer peripheral edge portions of the rear surface of the optical filter 2. The rear stopper 45 can come into contact with the optical filter 2 (the outer peripheral edge portion of the rear filter surface 12) from the rear X2, and prevents the optical filter 2 from moving to the rear X2.

  Here, the filter holding ring 3 is fixed by being screwed into the filter frame 4 until the rear end 3 a abuts against the front-facing surface of the rear stopper 45 provided on the filter frame 4. An adhesive 35 can be used to fix the filter holding ring 3 and the filter frame 4.

In a state in which the filter holding ring 3 is fixed to the filter frame 4, the ring-side annular rearward surface 27 continuous behind the ring-side male screw 25 and the frame-side annular forward surface 34 of the filter frame 4 are in contact with each other. Further, in a state where the filter holding ring 3 is fixed to the filter frame 4, the optical filter 2 can rotate around the axis L between the front stopper 21 and the rear stopper 45 of the filter frame 4. That is, a gap of about 0.01 mm to 0.02 mm is formed between the annular outer peripheral surface 14 of the optical filter 2 and the ring-side annular inner peripheral surface 24 of the filter holding ring 3. Further, when the front filter surface 11 of the optical filter 2 is brought into contact with the front stopper 21, the distance between the rear filter surface 12 of the optical filter 2 and the annular front end surface 45 a of the rear stopper 45 is 0.03 mm or less. The gap G1 is formed.

(Function and effect)
According to this example, the optical filter 2 is held by the camera filter frame 6 so as to be relatively rotatable about the axis L. Therefore, the stress (pressure) applied to the optical filter 2 held in the camera filter frame 6 is close to zero.

  In this example, when the optical filter 2 is brought into contact with the front stopper 21, the gap G between the optical filter 2 and the front surface 22a of the rear stopper 22 is 0.05 mm or less and is narrow. Further, the contact between the rear end 3a of the filter holding ring 3 on which the front stopper 21 is formed and the annular front end surface 45a of the rear stopper 45 accurately defines the dimension between the front stopper 21 and the rear stopper 45. Is done. Therefore, the optical filter 2 is not rattled between the front stopper 21 and the rear stopper 22, and the optical filter 2 is maintained in a state of being held coaxially with the filter holding ring 3.

  Further, in this example, since the filter frame 4 that holds the filter holding ring 3 from the outer peripheral side is provided, it is easy to provide the filter frame 4 with a lens barrel of the imaging lens or a mounting portion to the camera.

(Example 2)
Also in this example, similarly to the camera filter unit 1A ′ of the first embodiment, the filter holding ring 3 is provided with an adhesive injection hole 47 (through hole), and the filter holding ring is interposed via the adhesive injection hole 47. An adhesive 48 can be interposed between the optical filter 2 and the optical filter 2. In this way, the rotation of the optical filter 2 around the axis L can be prevented. Further, the posture of the optical filter 2 can be accurately defined as a posture in which the outer peripheral edge portion of the front filter surface 11 of the optical filter 2 is in contact with the annular rear end surface 21a of the front stopper 21, and the posture can be maintained.

(Reference Example 4)
9A is a longitudinal sectional view schematically showing the camera filter unit of Reference Example 4, and FIG. 9B is the vicinity of the outer peripheral edge portion of the optical filter 2 in the camera filter unit of Reference Example 4. It is the partial expanded sectional view which expanded. The camera filter unit 1 </ b> C of this example does not include the filter holding ring 3, and the optical filter 2 is held by a filter frame (tubular body) 4. Since the camera filter unit 1C of this example has a configuration corresponding to that of the camera filter unit 1 of Reference Example 1, the corresponding parts are denoted by the same reference numerals and description thereof is omitted.

  As shown in FIG. 9A, the camera filter unit 1C of the present invention includes an optical filter 2, a filter frame 4 in which the optical filter 2 is coaxially fitted on the inner peripheral side, and an inner peripheral side of the filter frame 4. And a retaining ring 7 attached to the. The filter frame 4 and the retaining ring 7 constitute a camera filter frame 6.

As shown in FIG. 9B, the filter frame 4 has a frame-side female screw 31, an annular stepped portion 51, an optical filter holding surface 52, and a rear-side stopper 53 on its inner peripheral surface from the front X1 toward the rear X2. Is provided. The frame-side female screw 31 is formed in a region having a constant width from the front end edge of the filter frame 4 toward the rear X2. The annular step portion 51 includes an annular inward surface 51a extending from the frame-side female screw 31 toward the rear X2 with a constant radial dimension, and a radial direction (a direction orthogonal to the axis L) from the rear end of the annular inward surface 51a. An annular forward surface 51b extending toward the circumferential side is provided. The optical filter holding surface 52 is an annular surface facing the inner peripheral side, and extends from the inner peripheral side end of the annular forward facing surface 51b toward the rear X2 with a constant radial dimension. The optical filter 2 is fitted on the inner peripheral side of the optical filter holding surface 52 and is held coaxially by the filter frame 4. There is a gap of about 0.01 mm to 0.02 mm on one side between the optical filter holding surface 52 and the annular outer peripheral surface 14 of the optical filter 2.

  The rear stopper 53 is an annular protrusion that protrudes from the rear end portion of the filter frame 4 to the inner peripheral side at a constant height. The rear stopper 53 includes an annular front end surface (forward facing surface) 53a facing the front X1 and an annular inner peripheral surface 53b facing the inner peripheral side. The annular inner peripheral surface 53 b of the rear stopper 53 is located on the inner peripheral side with respect to the annular chamfered surface 13 of the optical filter 2. The annular front end surface 53 a is a flat surface orthogonal to the axis L, and extends along the rear filter surface 12 of the optical filter 2. When viewed from the rear X2 in the axis L direction, the rear stopper 53 overlaps with the outer peripheral edge portion of the rear filter surface 12 and the annular chamfered surface 13 which are the outer peripheral edge portions of the rear surface of the optical filter 2. The rear stopper 45 can come into contact with the optical filter 2 (the outer peripheral edge portion of the rear filter surface 12) from the rear X2, and prevents the optical filter 2 from moving to the rear X2.

  The retaining ring 7 includes a front stopper 21 that protrudes inward on the inner peripheral surface thereof. The front stopper 21 is an annular protrusion. An annular rear end surface (rear facing surface) 21 a of the front stopper 21 is a flat surface orthogonal to the axis L. The front stopper 21 can come into contact with the optical filter 2 from the front X1, and prevents the optical filter 2 from moving forward X1. The retaining ring 7 includes a ring-side annular inner peripheral surface 24 that extends rearward X2 from an outer peripheral end of the annular rear end surface 21a of the front stopper 21. The inner diameter of the ring-side annular inner peripheral surface 24 is the same as the inner diameter of the optical filter holding surface 52.

  On the outer peripheral surface of the retaining ring 7, a ring-side male screw 25 is formed in a region having a constant width from the front end edge toward the rear X 2. The ring-side male screw 25 can be screwed with the frame-side female screw 31. On the outer peripheral surface of the retaining ring 7, a ring-side annular outer peripheral surface 26 having a constant diameter is provided behind the ring-side male screw 25.

  The retaining ring 7 is screwed from the front into the frame-side female screw 31 of the filter frame 4 with the ring-side male screw 25 holding the optical filter 2. Further, the retaining ring 7 is screwed in until the rear end 7 a of the retaining ring 7 comes into contact with the annular front surface 51 b of the annular step portion 51 of the filter frame 4, and is fixed coaxially to the filter frame 4. As a result, the optical filter 2 is held between the front stopper 21 provided on the retaining ring 7 and the rear stopper 53 provided on the filter frame 4. The retaining ring 7 and the filter frame 4 may be fixed with an adhesive 35.

  In a state where the retaining ring 7 is fixed to the filter frame 4, the ring-side annular outer peripheral surface 26 and the annular inward surface 51 a of the annular step portion 51 abut. Further, the ring-side annular inner peripheral surface 24 and the optical filter holding surface 52 form an annular surface having no step. Here, the width dimension W2 of the annular surface formed by the ring-side annular inner peripheral surface 24 and the optical filter holding surface 52 is longer than the thickness dimension D1 of the optical filter 2. In this example, the difference between the width dimension W2 of the annular surface formed by the ring-side annular inner peripheral surface 24 and the optical filter holding surface 52 and the thickness dimension D1 of the optical filter 2 is 0.03 mm or less.

In a state where the optical filter 2 is held between the front stopper 21 and the rear stopper 53, the optical filter 2 can be rotated relative to the filter frame 4 around the axis L. That is, a gap of about 0.01 mm to 0.02 mm is formed between the annular surface formed by the ring-side annular inner peripheral surface 24 and the optical filter holding surface 52 and the annular outer peripheral surface 14 of the optical filter 2. ing. Further, when the front filter surface 11 of the optical filter 2 is brought into contact with the front stopper 21, the distance between the rear filter surface 12 of the optical filter 2 and the rear stopper 53 is 0.03 mm.
The following gap G2 is formed.

(Function and effect)
According to this example, the optical filter 2 is held by the filter frame (tubular body) 4 in a state in which the optical filter 2 can relatively rotate about the axis L. Therefore, the stress (pressure) applied to the optical filter 2 held in the filter frame 4 is close to zero.

  In this example, when the optical filter 2 is brought into contact with the front stopper 21, the gap G2 formed between the rear stopper 53 and the optical filter 2 is 0.05 mm or less and is narrow. Furthermore, in this example, the contact between the rear end 7a of the retaining ring 7 on which the front stopper 21 is formed and the annular front end surface 53a of the rear stopper 53 results in a dimension between the front stopper 21 and the rear stopper 53. Accurately defined. Therefore, the optical filter 2 does not rattle between the front stopper 21 and the rear stopper 53.

  It is also possible to employ a configuration in which the front stopper 21 is provided integrally with the filter frame 4 and the rear stopper 53 is attached to the inner peripheral side of the filter frame 4. In this case, the front stopper 21 is an annular protrusion that protrudes inward from the filter frame 4. On the other hand, the rear stopper 53 is a stop ring that is inserted into the filter frame 4 from the rear and is fixed to the inner peripheral side of the filter frame 4.

(Example 3)
Also in this example, similarly to the camera filter unit 1A ′ of the first embodiment, the filter frame 4 is provided with an adhesive injection hole 47 (through hole), and the filter frame 4 An adhesive 48 can be interposed between the optical filters 2. In this way, the rotation of the optical filter 2 around the axis L can be prevented. Further, the posture of the optical filter 2 can be accurately defined by the posture in which the outer peripheral edge portion of the front filter surface 11 is in contact with the annular rear end surface 21a of the front stopper 21, and the posture can be maintained.

(Other embodiments)
FIG. 10 is a longitudinal sectional view schematically showing an imaging lens to which the present invention is applied. The imaging lens 1D is obtained by replacing the optical filter 2 with an optical lens (optical element) 8 in the camera filter unit 1A ′ of the first embodiment. Since the imaging lens 1D has the same configuration as the camera filter unit 1A ′ of Reference Example 2, the corresponding parts are denoted by the same reference numerals and description thereof is omitted.

  The optical lens 8 is a convex lens. The optical lens 8 includes a front lens surface 61 convex to the front X1 and a rear lens surface 62 convex to the rear X2. A tapered rear side chamfer 63 that is inclined toward the outer periphery toward the front X1 is continuous with the outer peripheral edge of the rear lens surface 62. An annular outer peripheral surface 64 having a constant diameter is continuous with the front end edge of the rear side chamfer 63. The front lens surface 61 is continuous with the front end edge of the annular outer peripheral surface 64.

The front stopper 21 provided on the filter holding ring 3 is inclined forward X1 toward the inner peripheral side, and the rearward surface 21a of the front stopper 21 is a tapered surface extending along the outer peripheral edge portion of the front lens surface 61. It has become. The front stopper 21 can come into contact with the optical lens 8 from the front X1, and prevents the optical lens 8 from moving forward X1. The rear stopper 22 is provided by bending the rear end portion of the filter holding ring 3 toward the inner peripheral side. The forward facing surface 22 a of the rear stopper 22 extends along the annular chamfered surface 63 of the optical lens 8. The rear side stopper 22 can contact the optical lens 8 from the rear X2, and prevents the optical lens 8 from moving to the rear X2. The optical lens 8 is held in a state of being relatively rotatable around the axis L with respect to the filter holding ring 3, but cannot be rotated by an adhesive 48 interposed between the filter holding ring 3 and the optical lens 8. Yes. The optical lens 8 is fixed with the front lens surface 61 in contact with the front stopper 21.

  Also in this example, a gap of about 0.01 mm to 0.02 mm is formed between the annular outer peripheral surface 64 of the optical lens 8 and the ring-side annular inner peripheral surface 24 of the filter holding ring 3. Further, when the front lens surface 61 of the optical lens 8 is brought into contact with the front stopper 21, the annular chamfered surface 63 of the rear lens surface 62 of the optical lens 8 and the tapered forward surface 22a of the rear stopper 22 are provided. A gap of 0.05 mm or less is formed between the two. The front stopper 21 may have the same shape as the front stopper 21 in the first embodiment. That is, it may be provided with an annular rear end surface (rear facing surface) that protrudes in a direction orthogonal to the axis L and orthogonal to the axis L.

  In such an imaging lens 1D, the stress applied to the optical lens 8 is close to zero. Therefore, when shooting at a high resolution that is many times as high as that of full high-definition, it is possible to obtain more beautiful captured images and captured moving images. Here, in each of the camera filter units 1, 1 </ b> A to 1 </ b> C of Reference Examples 1, 2, 3, and 4, the optical lens 8 can be mounted instead of the optical filter 2 to obtain an imaging lens.

  The holding structure of the optical member that coaxially arranges the optical element on the inner peripheral side of the cylindrical body and rotatably holds the optical element between the front stopper 21 and the rear stopper is provided in the photographing device and the projection device. It can also be used when installing. For example, a configuration corresponding to the camera filter unit 1 of Reference Example 1 can be employed when the optical filter 2 is mounted in an optical system of a photographing apparatus or a projection apparatus. In this case, the filter holding ring 3 holding the optical filter 2 so as to be relatively rotatable is fixed to the device. The second rear stopper 53 is mounted on the device via a distance adjustment mechanism that can adjust the distance to the optical filter 2.

Claims (10)

A cylindrical body in which an optical element is coaxially inserted on the inner peripheral side;
A front stopper capable of contacting the outer peripheral edge portion of the front surface of the optical element from the front in the axial direction;
A rear stopper adjacent to the optical element at the rear in the axial direction and facing the outer peripheral edge portion of the rear surface of the optical element;
An adhesive for fixing the optical element held in a rotatable state around the axis between the front stopper and the rear stopper to the cylinder so as not to rotate;
The cylindrical body includes a through hole penetrating in a direction intersecting the axial direction,
The front stopper is a protrusion that protrudes from the front end portion of the cylindrical body to the inner peripheral side,
The rear stopper is provided by bending the rear end portion of the cylindrical body to the inner peripheral side,
The adhesive is interposed between the cylindrical body and the optical element through the through hole and between the cylindrical body and the optical element ,
The optical element holding structure according to claim 1, wherein the optical element is fixed to the cylindrical body by the adhesive with a gap formed between the optical element and the front stopper . In claim 1,
The cylinder includes an annular groove on at least one of an outer peripheral surface and an inner peripheral surface,
The holding structure for holding an optical element, wherein the rear stopper is provided by bending an inner circumferential side portion of the cylindrical body where the annular groove is formed . In claim 1 or 2,
An optical element holding structure comprising a frame for holding the cylindrical body on an inner peripheral side . A cylindrical body in which an optical element is coaxially inserted on the inner peripheral side;
A front stopper capable of contacting the outer peripheral edge portion of the front surface of the optical element from the front in the axial direction;
A rear stopper adjacent to the optical element at the rear in the axial direction and facing the outer peripheral edge portion of the rear surface of the optical element;
An adhesive for fixing the optical element held in a rotatable state around the axis between the front stopper and the rear stopper to the cylinder so as not to rotate;
The cylindrical body includes a through hole penetrating in a direction intersecting the axial direction,
One of the front side stopper and the rear side stopper is formed integrally with the cylindrical body.
,
The other of the front side stopper and the rear side stopper is attached to the inner peripheral surface portion of the cylindrical body,
The adhesive is interposed between the cylindrical body and the optical element through the through hole and between the cylindrical body and the optical element,
The optical element holding structure according to claim 1, wherein the optical element is fixed to the cylindrical body by the adhesive with a gap formed between the optical element and the front stopper . In claim 4,
An optical element holding structure comprising a frame for holding the cylindrical body on an inner peripheral side . A cylindrical body in which an optical element is coaxially inserted on the inner peripheral side;
A front stopper capable of contacting the outer peripheral edge portion of the front surface of the optical element from the front in the axial direction;
A rear stopper adjacent to the optical element at the rear in the axial direction and facing the outer peripheral edge portion of the rear surface of the optical element;
An adhesive for fixing the optical element held in a rotatable state around the axis between the front stopper and the rear stopper to the cylinder so as not to rotate;
A frame for holding the cylindrical body on the inner peripheral side,
The cylindrical body includes a through hole penetrating in a direction intersecting the axial direction,
The front stopper is provided on the cylindrical body,
The rear stopper is provided on the frame;
The adhesive is interposed between the cylindrical body and the optical element through the through hole and between the cylindrical body and the optical element,
The optical element holding structure according to claim 1, wherein the optical element is fixed to the cylindrical body by the adhesive with a gap formed between the optical element and the front stopper . In claim 1,
Between the cylindrical body and the annular outer peripheral surface of the optical element facing the cylindrical body in a direction orthogonal to the axial direction, there is a gap of 0.01 mm to 0.02 mm in one piece. An optical element holding structure. The optical element holding structure according to any one of claims 1 to 7,
A filter frame for a camera, wherein an optical filter is held as the optical element. The holding structure for an optical element according to any one of claims 1 to 7,
An optical filter held on the inner peripheral side of the cylindrical body,
A camera filter unit characterized by comprising: The holding structure for an optical element according to any one of claims 1 to 7,
An optical lens held on the inner peripheral side of the cylindrical body,
An imaging lens comprising: